CiscoRTTMonDNS.pm

# NAME

probes::CiscoRTTMonDNS.pm - Probe for SmokePing

# SYNOPSIS

     *** Probes ***
     + CiscoRTTMonDNS
     + forks=50

     *** Targets ***
     + MyRouter-DNSserver
     menu = MyRouter->DNSserver
     title = RTTMon DNS lookup of www.foobar.com.au on DNSserver
     host = DNSserver.foobar.com.au
     probe=CiscoRTTMonDNS
     ++ PROBE_CONF
     ioshost = RTTcommunity@Myrouter.foobar.com.au
     name=www.foobar.com.au
     iosint = 10.33.22.11

# DESCRIPTION

A probe for smokeping, which uses the ciscoRttMon MIB functionality (``Service Assurance Agent'', ``SAA'') of Cisco IOS to time ( recursive, type A) DNS queries to a DNS server.

# PARAMETERS

The (mandatory) host parameter specifies the DNS server, which the router will use. This can be a DNS name, the smokeping host can resolve or a dotted-quad IP address.

The (mandatory) ioshost parameter specifies the Cisco router, which will send the DNS requests, as well as the SNMP community string on the router.

The (mandatory) name parameter is the DNS name to resolve.

The (optional) iosint parameter is the source address for the DNS packets. This should be one of the active (!) IP addresses of the router to get results. IOS looks up the target host address in the forwarding table and then uses the `interface(s)` listed there to send the DNS packets. By default IOS uses the (primary) IP address on the sending interface as source address for packets originated by the router.

# IOS VERSIONS

This probe only works with IOS 12.0(3)T or higher. It is recommended to test it on less critical routers first.

# INSTALLATION

To install this probe copy ciscoRttMonMIB.pm to ($SMOKEPINGINSTALLDIR)/lib and CiscoRTTMonDNS.pm to ($SMOKEPINGINSTALLDIR)/lib/probes.

The `router(s)` must be configured to allow read/write SNMP access. Sufficient is:

            snmp-server community RTTCommunity RW

    If you want to be a bit more restrictive with SNMP write access to the router, then consider configuring something like this

            access-list 2 permit 10.37.3.5
            snmp-server view RttMon ciscoRttMonMIB included
            snmp-server community RTTCommunity view RttMon RW 2

The above configuration grants SNMP read-write only to 10.37.3.5 (the smokeping host) and only to the ciscoRttMon MIB tree. The probe does not need access to SNMP variables outside the RttMon tree.

# BUGS

The probe does unnecessary DNS queries, i.e. more than configured under ``*** Database ***'' - ``pings'', because the RTTMon MIB only allows to set a total time for all queries in one measurement run (one ``life''). Currently the probe sets the life duration to ``pings''*2+3 seconds (2 secs is the timeout value hardcoded into this probe).

# SEE ALSO

http://people.ee.ethz.ch/~oetiker/webtools/smokeping/ http://www.switch.ch/misc/leinen/snmp/perl/

The best source for background info on SAA is Cisco's documentation on http://www.cisco.com and the CISCO-RTTMON-MIB documentation, which is available at: ftp://ftp.cisco.com/pub/mibs/v2/CISCO-RTTMON-MIB.my

# AUTHOR

Joerg.Kummer at Roche.com